Low profile introducer apparatus

ABSTRACT

An introducer apparatus includes an outer sleeve and an inner cannula received within the lumen of the outer sleeve. The outer sleeve has a profile such that at least a portion of the distal end of the outer sleeve tapers in the distal direction at an angle not exceeding about 2° relative to a longitudinal axis of the apparatus. The distal open end of the outer sleeve has a wall thickness not exceeding about 0.003 inch, and is sized such that a first wire guide is receivable therethrough. The inner cannula includes a tapered distal end portion. The inner cannula distal open end is sized such that a second wire guide is receivable therethrough, and the first wire guide is not receivable therethrough. The tapered distal portion of the inner cannula extends distal to the distal open end of the outer sleeve, such that a generally smooth diametrical transition is provided between the outer sleeve tapered portion and the open distal end of the inner cannula.

RELATED APPLICATION

The present application is a Continuation of U.S. application Ser. No.13/424,938 filed on Mar. 20, 2012, which is a Continuation of U.S.application Ser. No. 11/440,834 filed on May 25, 2006, which claimspriority to U.S. Provisional Application Ser. No. 60/685,188 filed onMay 27, 2005, the contents of which applications are is hereinincorporated by reference in their entirety.

BACKGROUND

1. Technical Field

The present invention relates to the field of introducer assemblies forproviding percutaneous access to the vascular system. More specifically,the invention relates to a low profile apparatus suitable forintroducing catheters and other interventional devices into the vascularsystem with a minimal amount of trauma to the patient.

2. Background Information

Many medical procedures require the percutaneous placement of aninterventional medical device, such as a catheter, into an artery orvein. Such interventional devices may be used for, among other things,blood pressure monitoring, blood sampling, and the administration offluids and medicaments to a patient.

Typically, such devices are introduced into the vascular system usingthe well-known Seldinger percutaneous entry technique. In the Seldingertechnique, the physician makes an oblique entry into the artery or veinwith a beveled needle. A wire guide is passed through the bore of theneedle into the artery or vein. The needle is thereafter withdrawn,leaving the wire guide in place. The catheter or other interventionaldevice is then passed over the wire guide, through the puncture, andinto the artery or vein at the needle puncture site. Once the catheteris in place, the wire guide can be withdrawn.

One of the disadvantages of this procedure is that the initial needlestick must normally be made with a needle that is large enough to acceptthe wire guide through its central bore. Conventional wire guides oftencomprise a tightly wound helical stainless steel wire coil. In order tohave sufficient rigidity to properly support and lead many standardcatheters and other interventional devices in common use in modernmedicine, such wire guides are typically constructed to have an outerdiameter in the range of about 0.035 to 0.038 inch (0.89 or 0.97 mm).This diameter of wire guide will typically pass through an 18 gaugethinwall needle. An 18 gauge needle typically has a 0.050 inch (1.27 mm)outer diameter (O.D.) and a 0.042 inch (1.07 mm) inner diameter (I.D.).

The 18 gauge needle is the most common sized needle used for initialvascular access, and has become a standard needle for use with theSeldinger technique for percutaneous catheterization. However, the O.D.of an 18 gauge needle is just large enough to damage tissue or causeexcessive bleeding if it does not enter the vessel correctly, or if itinadvertently penetrates an organ or other unintended body structure. Asa result, it is desirable to utilize a smaller gauge needle, such as a21 gauge thinwall needle, for initial entry. A 21 gauge thinwall needletypically has a 0.032 inch (0.81 mm) O.D. and a 0.022 inch (0.56 mm)I.D., or smaller. Needles of 21 gauge thinwall, or smaller, areconsidered small enough that they do not damage tissue or organs, orcause excessive bleeding if inserted off target. In addition, smallergauge needles generally have correspondingly shorter bevels at theneedle tip compared to the size of the bevel tip of an 18 gauge needle.Thus, it is much easier to get a short bevel into the lumen of a smallvessel than the longer bevel of the 18 gauge needle.

Unfortunately, the bore of a needle of 21 gauge, or smaller, is notlarge enough to enable a standard 0.035 inch or 0.038 inch (0.89 mm or0.97 mm) diameter wire guide to be passed therethrough. The largest wireguide that can be easily introduced into such small gauge needles isnormally a wire of 0.018 inch (0.46 mm) O.D. However, many diagnosticand interventional devices need at least a 0.035 inch (0.89 mm), andmore preferably a 0.038 inch (0.97 mm), diameter wire guide to providesufficient support to enable the physician to optimally introduce andmanipulate the device through the vasculature over the wire. Thus,unless a larger diameter wire guide is introduced into the vasculature,many such devices cannot be successfully introduced.

U.S. Pat. No. 4,650,472 describes an apparatus which enables a physicianto introduce a medical device, such as a catheter, into the body of apatient by making the initial puncture with a small gauge needle, suchas a 22 gauge (0.028 inch; 0.72 mm O.D.) needle, in place of the largerconventional 18 gauge needle. The '472 patent is incorporated byreference herein. A 0.018 inch (0.46 mm) outer diameter wire guide isinitially inserted through the bore of the small gauge (e.g. 22 gauge)needle. The needle is thereafter withdrawn, and a removable innercannula, or dilator, is provided over the wire guide but inside an outersleeve portion of the catheterization apparatus. This removable innercannula has a tapered tip, and provides a transition between the largedistal opening of the outer sleeve and the 0.018 inch wire guide. Theinner cannula is generally about 0.038 inch (0.97 mm) O.D., and theouter sleeve is sized to fit over the inner cannula.

The outer sleeve and the inner cannula of the apparatus disclosed in the'472 patent are normally inserted into the blood vessel in tandem. Thediametrical transition of the leading end of this tandem is intended tominimize the trauma that may otherwise be caused by the insertion of alarge diameter outer sleeve over a small diameter wire guide. Once theouter sleeve is properly positioned within the blood vessel, the innercannula and the smaller wire guide can be withdrawn, leaving the outersleeve in place. A larger (0.035 to 0.038 inch) (0.89 to 0.97 mm) wireguide can then be introduced through the outer sleeve and into thevessel. If desired, the outer sleeve can thereafter be removed from thepatient, leaving the larger wire guide in the vessel ready to accept acatheter or other interventional device. The apparatus of the '472patent has been successfully used to percutaneously insert a medicaldevice, such as a catheter, having a large outer diameter into a bloodvessel when the initial insertion is made with an introducer needle anda wire guide which are much smaller in diameter than the distal openingof the catheter.

The apparatus of the '472 patent thus enables the physician to introducelarger diagnostic and interventional devices into a vessel than wouldotherwise be possible in a procedure in which initial vessel entry hasbeen made with a small gauge needle. When the apparatus is inserted intothe vessel as described, however, the physician must exert sufficientforce to overcome the resistance provided at the “bump” that is presentat the transition between the distal end of the outer sleeve and theunderlying portion of the inner cannula. If this force is not carefullycontrolled, the physician may inadvertently exert too great a force toovercome the bump, and thereby puncture the side of the vessel oppositethe initial stick. Thus, although the device of the '472 patent may besuccessfully used to introduce large devices when initial entry is madewith a small gauge needle, it is nonetheless desired to further improvethis device, by providing a design which reduces the amount of forcerequired to insert the outer sleeve into the vessel, and thereby reducesthe possibility of an inadvertent puncture of the opposing vessel wall.

BRIEF SUMMARY

The problems of the prior art are addressed by the apparatus and methodof the present invention.

In one form thereof, the invention comprises an introducer apparatuscomprising an outer sleeve and an inner cannula. The outer sleeve has alumen extending longitudinally therethrough, and has a profile such thatat least a portion of the outer sleeve tapers toward the outer sleevedistal end at an angle not exceeding about 2° relative to a longitudinalaxis of the apparatus. The outer sleeve has a distal open end sized suchthat a first wire guide is receivable therethrough. The distal open endof the outer sleeve has a wall thickness not exceeding about 0.003 inch.The inner cannula has a lumen extending longitudinally therethrough, andis sized to be received within the lumen of the outer sleeve. The innercannula has a portion that tapers toward the inner cannula distal end.The inner cannula distal open end is sized such that a second wire guideis receivable therethrough, and the first wire guide is not receivabletherethrough. The tapered distal portion of the inner cannula extendsdistal to the distal open end of said outer sleeve, and has a profilesuch that a generally smooth diametrical transition is provided betweenthe outer sleeve tapered portion and the inner cannula open end.

In another form thereof, the invention comprises a method of inserting awire guide into a body vessel of a patient for use in introducing amedical interventional device thereover. An introducer system comprisesan introducer needle having an inner bore that does not exceed about0.018 inch (0.46 mm) in diameter; a first wire guide having an outerdiameter not less than about 0.035 inch (0.89 mm); a second wire guidehaving an outer diameter not greater than about 0.018 inch (0.46 mm) andbeing receivable in a bore of the introducer needle; and an introducerapparatus comprising an outer sleeve and an inner cannula. The innercannula is removably received in a lumen of the outer sleeve. The outersleeve has a profile such that a distal portion of the sleeve taperstoward the sleeve distal end at an angle not exceeding about 2° with alongitudinal axis of the sleeve. The outer sleeve distal open end issized such that the first wire guide is receivable therethrough. Theinner cannula has a lumen extending therethrough, and has a distalportion that tapers toward the inner cannula distal end. The innercannula distal open end is sized such that the second wire guide isreceivable therethrough and the first wire guide is not receivabletherethrough. The tapered distal portion of the inner cannula extendsdistal to the distal open end of the outer sleeve, and has a profilesuch that a generally smooth diametrical transition is provided betweenthe outer sleeve tapered portion and the inner cannula open end. Theneedle is injected into the body vessel, and the second wire guide isinserted through the needle bore such that a distal end of the wireguide extends beyond the needle in the body vessel. The needle iswithdrawn from the body vessel over the second wire guide, ant theintroducer apparatus is thereafter introduced over the wire guide suchthat the respective distal ends of the outer sleeve and inner cannulaare in the body vessel. The second wire guide is withdrawn from theintroducer apparatus while maintaining the introducer apparatus in thebody vessel. The inner cannula is separated from the outer sleeve, andremoved from the vessel while maintaining the outer sleeve in the bodyvessel. The first wire guide is guided through the outer catheter suchthat a distal end of the first wire guide extends beyond the outersleeve in the body vessel. The outer cannula may then be withdrawn overthe first wire guide.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of the distal end portion of a prior artintroducer apparatus suitable for entry into the vascular system with asmall gauge needle;

FIG. 2 is an enlarged sectional view of the outer sleeve of theapparatus of FIG. 1;

FIG. 3 illustrates one embodiment of a low profile introducer apparatusof the present invention;

FIG. 4 illustrates a side view of the outer sleeve of the low profileintroducer apparatus of FIG. 3;

FIG. 5 illustrates an enlarged distal end portion of the outer sleeveshown in FIG. 4;

FIG. 6 illustrates a side view of the inner cannula of the low profileintroducer apparatus of FIG. 3;

FIG. 7 is a side view of a small gauge needle suitable for use inconnection with the low profile introducer apparatus of the presentinvention;

FIG. 8 is a graph illustrating the relationship between compressiveextension and compressive load for specimens 1-15 of an embodiment ofthe inventive apparatus;

FIG. 9 is a graph illustrating the relationship between compressiveextension and compressive load for specimens 16-30 of an embodiment ofthe inventive apparatus;

FIG. 10 is a graph illustrating of relationship between compressiveextension and compressive load for specimens 1-15 of a prior artapparatus; and

FIG. 11 is a graph illustrating the relationship between compressiveextension and compressive load for specimens 16-30 of the prior artapparatus.

DETAILED DESCRIPTION OF THE DRAWINGS AND THE PRESENTLY PREFERREDEMBODIMENTS

For the purposes of promoting an understanding of the principles of theinvention, reference will now be made to the embodiments illustrated inthe drawings, and specific language will be used to describe the same.It should nevertheless be understood that no limitation of the scope ofthe invention is thereby intended, such alterations and furthermodifications in the illustrated device, and such further applicationsof the principles of the invention as illustrated therein beingcontemplated as would normally occur to one skilled in the art to whichthe invention relates.

In the following discussion, the terms “proximal” and “distal” will beused to describe the opposing axial ends of the inventive apparatus, aswell as the axial ends of various related components. The term“proximal” is used in its conventional sense to refer to the end of theapparatus (or component) that is closest to the operator during use ofthe collar. The term “distal” is used in its conventional sense to referto the end of the apparatus (or component) that is initially insertedinto the patient, or that is in closest proximity to the patient.

FIG. 1 is a side view of the distal end portion of a prior artintroducer apparatus 100 for introducing a medical device into a bodyvessel when the initial stick is made with a small gauge needle.Introducer apparatuses of this type are further described in theincorporated-by-reference U.S. Pat. No. 4,650,472. FIG. 1 illustrates atypical dimensional relationship between an outer sleeve 102, innercannula 110 and small diameter wire guide 120. Outer sleeve 102 includesa distal portion 104 that tapers to outer sleeve distal end 106. Innercannula 110 also includes a distal portion 112 that tapers to innercannula distal end 114. In the example shown, wire guide 120 extendsfrom inner cannula distal end 114 in the normal fashion.

FIG. 2 is an enlarged sectional view of outer sleeve 102 of prior artapparatus 100. Generally, for an outer sleeve having a typical outerdiameter of about 5 French and a length of about 10 cm or more, thelength a of tapered portion 104 in this prior art apparatus isapproximately 4 (±1) mm. The thickness b of the wall of sleeve 102 atdistal end 106 is about 0.004 (±0.0005) inch [0.10 (±0.013) mm]. Taperedarea 104 extends at an angle of greater than about 3°, typically greaterthan 3.5° from a longitudinal axis.

FIG. 3 illustrates one embodiment of an introducer apparatus 10 of thepresent invention. Introducer apparatus 10 comprises an outer sleeve 12and an inner cannula 30 that extends through a lumen 17 (FIG. 5) in theouter sleeve. A small diameter wire guide 40 extends through a lumen(not shown) in inner cannula 30. Outer sleeve 12 is further illustratedin FIG. 4, and inner cannula 30 is further illustrated in FIG. 6. FIG. 5is an enlarged view of the distal end portion of outer sleeve 12.

Like the prior art structure shown in FIGS. 1 and 2, apparatus 10 may beused for introducing a medical device into a body vessel using a smallgauge needle, e.g., a needle of 21 gauge or smaller. One example of asuitable small gauge needle 80 is shown in FIG. 7. Needle 80 is aconventional small gauge needle, and includes a stainless steel shaft 82having a lancet beveled tip 84, and a lumen 86 therethrough. A standardhub 88 may be attached at the proximal end of needle 80.

Unlike the prior art structure, outer sleeve 12 of the present inventionis dimensioned to provide a very gradual transition between the distalend of the outer sleeve and the inner cannula. This transition is muchsmoother, and occurs in a much more gradual manner over a greatertapered length 14 of the outer sleeve, when compared to the much moreabrupt transition of the tapered portion 104 of the prior art deviceshown in FIG. 1. The smooth, gradual transition at the distal end of theinventive apparatus forms a very sleek profile that enables theapparatus to be smoothly inserted into, and passed through, the initialbody opening and the underlying tissue. As a result, the patientexperiences reduced trauma, both at the initial insertion point and asthe apparatus is further inserted into a body vessel of the patient.

As best shown in FIGS. 4 and 5, outer sleeve 12 includes a main shaftportion 13, having a distal portion 14 and a proximal portion 15. Distalportion 14 tapers to outer sleeve distal end 16. The proximal end ofproximal portion 15 is received within a conventional hub 18. As shownin FIG. 6, inner cannula 30 also includes a main shaft portion 33,having a distal portion 34 and a proximal portion 35. Distal portion 34tapers to an inner cannula distal end 36. The proximal end of proximalportion 35 is received within a conventional hub 38. Respective hubs 18,38 are sized and shaped for locking engagement when the introducerapparatus is fully assembled. Hubs 18, 38 may be of any conventionaldesign that permits releasable engagement therebetween, the specificdesigns shown in the figures merely representing examples of suitablehubs. The specific design of the hubs is not germane to an understandingof the present invention, and therefore, no further description of thehubs is provided.

When introducer apparatus 10 is fully assembled as shown in FIG. 3,inner cannula 30 is received within lumen 17 of outer sleeve 12, anddistal end portion 34 of inner cannula 30 extends beyond distal portion14 of the outer sleeve. Unlike the tapered portion 104 of the outersleeve in prior art structure 100, distal portion 14 of the outer sleeveof inventive apparatus 10 tapers in a much more gradual fashion to thedistal end of the sleeve. Thus, the length c (FIG. 4) of tapered portion14 of the inventive sleeve is longer, and in some embodimentsconsiderably longer, than length a (FIG. 2) of the more abrupt taperedportion of a prior art device of the same outer diameter. Thisdifference in length c when compared to length a illustrates the moregradual taper, or transition, from the outer sleeve to the inner cannulain the inventive device, when compared to the prior art structure.Preferably, the length c of the tapered portion of the inventive sleeveis between about 5 and 50 mm, more preferably between about 8 and 20 mmlong.

As a result of the extended tapered length of the inventive design, thesleek profile of the inventive sleeve results in a wall thickness d ofsleeve distal end 16 that is less, and in many cases considerably less,than the thickness of the wall at the distal end of the prior artdesign. Preferably, thickness d is between about 0.0005 and 0.003 inch[0.013 and 0.076 mm], more preferably between about 0.0005 and 0.0015inch [0.013 and 0.38 mm], and most preferably, about 0.001 inch (±0.0005inch) [0.025±0.013 mm]. The wall thickness of the prior art design istypically about 0.004 inch (±0.0005 inch) [0.10±0.013]. As a result,tapered distal end 14 of the inventive sleeve has a much more gradualtaper than that of the prior art device, and tapers to a much narrowerwall thickness at the distal end. Preferably, tapered area 14 extends atan angle not exceeding about 2° from the longitudinal axis, andpreferably about 1-1.5°.

The comparative dimensions provided hereinabove are for outer sleeves ofsimilar French sizes, and in the examples given, for a 5 French outersleeve. In this event, length c of the inventive design is about 15 mm.This compares to length a in the prior art design of about 4 mm. For asmaller French size, such as 4 French, the length c will normally becorrespondingly smaller, such as about 8 mm for the inventive design.For a larger French size, such as 6 French, the length c will normallybe correspondingly larger, such as about 17 mm. For comparison, thelength a of a prior art 4 French sleeve is typically about 2 mm, and thelength a of a prior art 6 French sleeve is typically about 5 mm. In eachcase, the length of the tapered area of the prior art sleeve issignificantly shorter than the length of the tapered portion of theinventive sleeve.

Those skilled in the art will appreciate that the inventive apparatus 10can be formed to have any conventional size for its intended purposes.Preferably, the outer sleeve will generally have a diameter betweenabout 2 and 10 French, more preferably between 4 and 6 French, and mostpreferably, about 5 French. However, the teachings of the presentinvention are also applicable to sleeves of even larger diameters, aslong as the length of the sleeve can accommodate a taper as described.

The outer sleeve is preferably sized for insertion therein of innercannulae of the type commonly used in such devices for catheterizationwith a small gauge needle. Thus, a conventional apparatus of the typeknown in the art can be utilized, with the exception of the outersleeve, which will be dimensioned as disclosed herein. In addition tothe other dimensions provided hereinabove, the lumen 15 of the outersleeve may have a diameter similar to that of existing devices. Atypical lumen diameter is about 0.04 inch (1 mm). The dimensionsprovided hereinabove are only examples of suitable dimensions for anouter sheath, and sheaths of other dimensions are also within the scopeof the invention.

The sleek design of apparatus 10, and more particularly, of outer sleeve12, enables the inventive apparatus to be introduced into a body vesselof a patient with a minimum of trauma. Certain tests were carried out tosimulate the amount of force that a physician must exert during theinsertion of the inventive introducer apparatus through the skin at abody opening. This force was compared to the amount of force that mustbe exerted while inserting a prior art introducer apparatus through asimilar body opening. The prior art apparatus included a 5 French outersleeve, a tapered distal sleeve portion having a length a of 4 mm and awall thickness b at its distal end of about 0.004 inch. The taperedportion of the prior art apparatus tapered at an angle of about 3degrees. For comparison, the inventive apparatus included a 5 Frenchouter sleeve, a tapered distal portion having a length c of 15 mm and awall thickness d at its distal end of about 0.001 inch. The taperedportion of the prior art apparatus tapered at an angle of about 1degree. The inner cannulae used in each test were identical, having adiameter of 3 French and a length of about 120 mm. The length of theprior art sleeve was about 100 mm, and the length of the inventivesleeve was about 105 mm.

A sheet of 0.038 inch thick condensed silicone with a translucent colorwas provided to simulate the skin of a patient. Silicone sheets of thistype are commercially available from, among others, AAA-Acme RubberCompany, of Tempe, Ariz., under the name Dura Silicone. In each case,the initial puncture through the silicone sheet was made with a 21 gaugeneedle. A 0.018 inch wire guide was inserted through the bore of theneedle in conventional fashion. The needle was thereafter withdrawn overthe wire guide, and the sleeve/cannula apparatus was inserted over thewire guide and through the silicone sheet.

Simulations were performed on thirty specimens of the inventiveapparatus and thirty specimens of a prior art apparatus. The testingconditions were intended to be as close to identical on all specimens aspossible. The tests were designed to simulate and record the maximumload (in lbf) that is exerted on the skin as the introducer apparatusinitially enters the skin through the needle puncture, the compressiveextension (in mm) at the maximum load encountered during insertion, andthe compressive load (in lbf) at 47 mm (with the inventive apparatus)and 42 mm (with the prior art apparatus), respectively. The compressiveextension at the maximum load recites the depth at which maximum forceis exerted during insertion. The compressive loads at 47 and 42 mmrepresent readings taken past the taper and transition length. Thesereadings indicate that the push force needed to traverse the transitionbetween the inner cannula and the outer sleeve with the inventive designis less than the force needed to traverse the sleeve. On the other hand,with the prior art device, the push force at the point of transitionconsiderably exceeds the force along the sleeve.

The results of the tests on the 30 specimens of the inventive apparatusare shown below in Table 1.

TABLE 1 Compressive Com- Max- extension at pressive imum Maximum load atSpecimen Load Comp. load 47 mm Label (lbf) (mm) (lbf) Comment 1 0.314.47458 0.27933 Pushed without incident 2 0.35 4.18979 0.32828 Pushedwithout incident 3 0.32 32.73474 0.28809 Pushed without incident 4 0.4036.24515 0.26727 Pushed without incident 5 0.39 5.53499 0.24153 Pushedwithout incident 6 0.33 5.00999 0.23552 Pushed without incident 7 0.3635.05036 0.20435 Pushed without incident 8 0.29 4.70999 0.23899 Pushedwithout incident 9 0.28 47.49513 0.24798 Pushed without incident 10 0.365.23041 0.23015 Pushed without incident 11 0.35 41.46015 0.18996 Pushedwithout incident 12 0.43 22.76017 0.25893 Pushed without incident 130.37 5.86520 0.18430 Pushed without incident 14 0.34 4.84437 0.26116Pushed without incident 15 0.29 46.74514 0.22182 Pushed without incident16 0.33 34.20495 0.24218 Pushed without incident 17 0.35 5.20999 0.25428Pushed without incident 18 0.36 5.63499 0.21307 Pushed without incident19 0.36 5.34978 0.21285 Pushed without incident 20 0.37 47.17951 0.18557Pushed without incident 21 0.36 46.88972 0.24057 Pushed without incident22 0.36 5.47499 0.22677 Pushed without incident 23 0.38 6.07978 0.19394Pushed without incident 24 0.33 5.61041 0.18142 Pushed without incident25 0.28 4.99520 0.19651 Pushed without incident 26 0.33 41.46952 0.19551Pushed without incident 27 0.39 5.98520 0.16382 Pushed without incident28 0.37 36.46015 0.15755 Pushed without incident 29 0.38 5.68999 0.20767Pushed without incident 30 0.34 40.59056 0.17002 Pushed without incidentMean 0.35 19.97250 0.22398 Standard 0.03480 17.70996 0.03969 DeviationMinimum 0.28 4.18979 0.15755 Maximum 0.43 47.49513 0.32828 Rate 1 150.0mm/min Data capture Manual Control mode 1 Compressive extension Start oftest Temperature (deg C.) 21.0 Start of Test Relative Humidity (%) 37.0End of test Temperature (deg C.) 21.0 End of test Relative Humidity (%)29.0

The data of Table 1 is illustrated graphically in FIG. 8 for specimens 1to 15, and in FIG. 9 for specimens 16 to 30 of the inventive apparatus.In the figures, the “zero point” (“0”) of the “compressive extension”and the “compressive load” represents the point where the inner cannulainitially touches the sheet as it is urged forwardly for insertion.

The results of the tests on the 30 specimens of the conventional, priorart apparatus are shown below in Table 2.

TABLE 2 Compressive Com- Max- extension at pressive imum Maximum load atSpecimen Load Comp. load 42 mm Label (lbf) (mm) (lbf) Comment 1 0.6011.28040 0.17221 Pushed without incident 2 0.62 11.46957 0.13470 Pushedwithout incident 3 0.61 9.84978 0.21689 Pushed without incident 4 0.6110.67436 0.17909 Pushed without incident 5 0.57 9.78998 0.24985 Pushedwithout incident 6 0.61 9.47436 0.28167 Pushed without incident 7 0.5910.46415 0.21618 Pushed without incident 8 0.59 11.01998 0.14473 Pushedwithout incident 9 0.57 9.48040 0.28587 Pushed without incident 10 0.6310.59957 0.19785 Pushed without incident 11 0.60 10.93436 0.15891 Pushedwithout incident 12 0.62 10.51498 0.18479 Pushed without incident 130.59 10.62915 0.18130 Pushed without incident 14 0.61 11.20019 0.16731Pushed without incident 15 0.57 10.39457 0.18708 Pushed without incident16 0.67 10.64936 0.22800 Pushed without incident 17 0.58 9.64540 0.28844Pushed without incident 18 0.57 10.12457 0.21000 Pushed without incident19 0.57 9.97436 0.21853 Pushed without incident 20 0.63 10.49519 0.20705Pushed without incident 21 0.59 10.71936 0.17773 Pushed without incident22 0.61 11.48415 0.12394 Pushed without incident 23 0.60 9.99478 0.23544Pushed without incident 24 0.60 10.29978 0.22631 Pushed without incident25 0.57 10.59540 0.21824 Pushed without incident 26 0.57 10.419570.18823 Pushed without incident 27 0.57 11.18477 0.09785 Pushed withoutincident 28 0.53 9.67999 0.26979 Pushed without incident 29 0.5810.18103 0.26243 Pushed without incident 30 0.62 10.91498 0.16288 Pushedwithout incident Mean 0.60 10.47128 0.20244 Standard 0.02679 0.571580.04818 Deviation Minimum 0.53 9.47436 0.09785 Maximum 0.67 11.484150.28844 Rate 1 150.0 mm/min Data capture Manual Control mode 1Compressive extension Start of test Temperature (deg C.) 21.0 Start ofTest Relative Humidity (%) 32.0 End of test Temperature (deg C.) 21.0End of test Relative Humidity (%) 30.0

The data of Table 2 is illustrated graphically in FIG. 10 for specimens1 to 15, and in FIG. 11 for specimens 16 to 30 of the prior artapparatus.

As demonstrated by the simulations, considerably more force is requiredto enter the skin and underlying tissue when utilizing the prior artapparatus than with the inventive apparatus. This is particularly trueat the point where the distal end of the outer sleeve initiallypenetrates the skin. This is demonstrated in the Tables, and isgraphically illustrated by the respective curves shown in FIGS. 8-11.The x-axis of the graphs represents the compressive extension, or inother words, the length of insertion (in mm) of the apparatus throughthe skin. The y-axis represents the compressive load, or in other words,the force (in lbf) that is exerted by the physician upon insertion ofthe apparatus through the skin. As shown in each of the graphs of FIGS.8-11, the compressive load builds as the apparatus is advanced into theskin until the inner cannula has initially penetrated the skin. This isrepresented by the first peak in each of the figures. In both the priorart apparatus and the inventive apparatus (e.g., in each of the FIGS.8-11), the first peak indicates a maximum compressive load that istypically between about 0.30 and 0.40 lbf.

Upon insertion of the inner cannula through the skin an immediatedecrease in force is observed once the initial penetration, or puncture,has been completed. As the apparatus is further inserted, the force onceagain builds, to represent the force required for the outer sleeve topenetrate the skin. As illustrated in FIGS. 10 and 11 of thissimulation, and as documented in Table 2, considerable force is requiredfor the outer sleeve of the prior art apparatus to penetrate the skin.This is shown as the large (second) peak. As shown, a maximumcompressive load of from about 0.53 to 0.63 lbf must typically beexerted when the outer sleeve of the prior art apparatus penetrates theskin. The mean value of maximum compressive load of all thirty prior artspecimens is indicated as 0.60 lbf.

For comparison, as illustrated in FIGS. 8 and 9, and as documented inTable 1, a much smaller maximum compressive load is required when theouter sleeve of the inventive apparatus penetrates the skin. Once again,this is graphically shown by viewing the second peak in each of thesefigures. This peak illustrates that a compressive load of only about0.20 to 0.30 lbf is typically required at the insertion point of theouter sleeve. The reduction in force required with the inventiveapparatus when compared to the prior art apparatus is dramaticallyindicated by the absence of the large second peak in the inventivespecimens (FIGS. 8 and 9). This indicates a much smoother insertion whencompared to the prior art apparatus. The mean value of the maximumcompressive load of all thirty of the inventive specimens is indicatedas 0.35 lbf. In most of the inventive specimens, the maximum compressiveload does not even occur at this outer sleeve insertion point (secondpeak), but rather, occurs either during the initial puncture, or laterduring the insertion procedure as the tapered outer sleeve continues tobe pushed through the skin.

The inventive apparatus comprising the outer sleeve and inner cannulacan be provided as a combined apparatus, or as separate components.Similarly, the remaining components discussed herein, such as the wireguide(s) and the needle, can be provided with the outer sleeve and innercannula as a kit, or as separate components. The individual componentsare well known, and with the exception of the dimensional differences ofthe outer sleeve as described, may be formed in conventional manner andof well known compositions. Although the outer sleeve and inner cannulacan be formed of any materials suitable for their intended use,preferably they will be formed from a suitable polymer well known forsuch use, such as polyethylene.

It is therefore intended that the foregoing detailed description beregarded as illustrative rather than limiting, and that it be understoodthat it is the following claims, including all equivalents, that areintended to define the spirit and scope of this invention.

1. An introducer apparatus, comprising: an outer sleeve having proximaland distal open ends, and having a lumen extending longitudinallytherethrough, said outer sleeve having a profile such that at least aportion of said outer sleeve tapers toward said outer sleeve distal endat an angle not exceeding about 2° relative to a longitudinal axis ofthe apparatus, said distal open end of said outer sleeve having a wallthickness not exceeding about 0.003 inch; and an inner cannula havingproximal and distal open ends, and having a lumen extendinglongitudinally therethrough, said inner cannula sized to be receivedwithin the lumen of said outer sleeve, said inner cannula having aportion that tapers toward the inner cannula distal end, said tapereddistal portion of said inner cannula extending distal to the distal openend of said outer sleeve and having a profile such that a generallysmooth and gradual diametrical transition is provided from the outersleeve tapered portion and through said inner cannula open end; andwherein the greatest radial extent of the inner cannula is less than theinner diameter of the outer sleeve.
 2. The apparatus of claim 1, whereinsaid outer sleeve tapered portion comprises between about the distal 5and 50 mm of said outer sleeve.
 3. The apparatus of claim 2, whereinsaid outer sleeve tapered portion comprises between about the distal 8and 20 mm of said outer sleeve.
 4. The apparatus of claim 3, whereinsaid outer sleeve tapered portion comprises about the distal 15 mm ofsaid outer sleeve.
 5. The apparatus of claim 1, wherein said outersleeve tapered portion is tapered at an angle of between about 0.5° and2°.
 6. The apparatus of claim 5, wherein said outer sleeve taperedportion is tapered at an angle between about 1° and 1.5°.
 7. Theapparatus of claim 1, wherein said distal open end of said outer sleevehas a wall thickness of between about 0.0005 and 0.0015 inch.
 8. Theapparatus of claim 7, wherein said distal open end of said outer sleevehas a wall thickness of about 0.001 inch.
 9. The apparatus of claim 1,wherein said outer sleeve has an outer diameter not exceeding about 6French.
 10. The apparatus of claim 9, wherein said outer diameter isbetween about 4 and 6 French.
 11. The apparatus of claim 10, whereinsaid diameter is about 5 French.
 12. An introducer kit comprising: ahollow thinwall needle, said needle having an outer diameter that doesnot exceed about 21 gauge (0.032 inch; 0.81 mm), and an inner diameterthat does not exceed about 0.018 inch (0.46 mm); a first wire guide,said first wire guide having an outer diameter not less than about 0.035inch (0.89 mm); a second wire guide, said second wire guide receivablein a bore of said needle; an outer sleeve, said outer sleeve havingproximal and distal open ends and having a lumen extendinglongitudinally therethrough, said outer sleeve having a profile suchthat a distal portion of said outer sleeve tapers toward said outersleeve distal end at an angle not exceeding about 2° relative to alongitudinal axis of the apparatus, said outer sleeve tapered portioncomprising between about the distal 8 and 20 mm of said outer sleeve,said outer sleeve having an outer diameter that does not exceed about 6French and having a distal open end sized such that said first wireguide is receivable therethrough, said distal end of said outer sleevehaving a wall thickness between about 0.0005 and 0.0015 inch; and aninner cannula, said inner cannula having proximal and distal open endsand having a lumen extending longitudinally therethrough, said innercannula sized to be received within the lumen of said outer sleeve, saidinner cannula having a portion that tapers toward the inner cannuladistal end, said tapered distal portion of said inner cannula extendingdistal to the distal open end of said outer sleeve and having a profilesuch that a generally smooth and gradual diametrical transition isprovided from the outer sleeve tapered portion and through said innercannula open end; and wherein the greatest radial extent of the innercannula is less than the inner diameter of the outer sleeve.
 13. The kitof claim 12, wherein said outer sleeve tapered portion comprises thedistal 15 mm of said outer sleeve.
 14. The kit of claim 13, wherein saiddistal open end of said outer sleeve has a wall diameter of about 0.001inch (0.0254 mm).
 15. The kit of claim 14, wherein said outer sleeve hasan outer diameter that does not exceed about 5 French.
 16. A method ofinserting a wire guide into a body vessel of a patient for use inintroducing a medical interventional device, comprising: providing anintroducer system, said system comprising an introducer needle having anouter diameter that does not exceed about 21 gauge (0.032 inch; 0.81 mm)and an inner diameter that does not exceed about 0.018 inch (0.46 mm); afirst wire guide having an outer diameter not less than about 0.035 inch(0.89 mm); a second wire guide having an outer diameter not greater thanabout 0.018 inch (0.46 mm) and being receivable in a bore of saidintroducer needle; and an introducer apparatus comprising an outersleeve and an inner cannula, said inner cannula removably received in alumen of said outer sleeve, said outer sleeve having proximal and distalopen ends and a profile such that a distal portion of said outer sleevetapers toward said sleeve distal end at an angle not exceeding about 2°with a longitudinal axis of the sleeve, said outer sleeve distal openend sized such that said first wire guide is receivable therethrough,said inner cannula having proximal and distal open ends and a lumenextending therethrough, and having a portion that tapers toward theinner cannula distal end, said tapered distal portion of said innercannula extending distal to the distal open end of said outer sleeve andhaving a profile such that a generally smooth and gradual diametricaltransition is provided from the outer sleeve tapered portion and throughsaid inner cannula open end; and wherein the greatest radial extent ofthe inner cannula is less than the inner diameter of the outer sleeve;injecting said needle into said body vessel; guiding said second wireguide through said needle bore such that a distal end of said wire guideextends beyond said needle in said body vessel; withdrawing said needlefrom said body vessel over said second wire guide; introducing saidintroducer apparatus over said second wire guide such that therespective distal ends of said outer sleeve and inner cannula are insaid body vessel; wherein said introducing step comprises inserting saiddistal end of said inner cannula into said body vessel at a firstinsertion force, and inserting said introducer apparatus at a junctureof said outer sleeve distal open end and said inner cannula at a secondinsertion force, such that said second insertion force does not exceedsaid first insertion force; withdrawing said second wire guide from saidintroducer apparatus while maintaining the introducer apparatus in thebody vessel; separating the inner cannula from the outer sleeve, andremoving the inner cannula while maintaining the outer sleeve in thebody vessel; and guiding said first wire guide through said outercatheter such that a distal end of said first wire guide extends beyondsaid outer sleeve in said body vessel.
 17. The method of claim 16,further comprising: withdrawing said outer cannula over said first wireguide.
 18. The method of claim 16, wherein said angle is about 1°. 19.The method of claim 18, wherein said distal open end of said outercatheter has a thickness less than about 0.003 inch.
 20. The method ofclaim 18, wherein said distal open end of said outer catheter has athickness of about 0.001 inch.
 21. The apparatus of claim 1, whereinsaid apparatus is structured such that an insertion force required forinsertion of said apparatus through a body vessel at a juncture of saidouter sleeve distal open end and said inner cannula does not exceed aninsertion force required for an initial insertion of a distal end ofsaid inner cannula through said body vessel.
 22. The apparatus of claim1, wherein said apparatus is structured such that a lesser insertionforce is required for insertion of said apparatus through a body vesselat a juncture of said outer sleeve distal open end and said innercannula than is required for an initial insertion of a distal end ofsaid inner cannula through said body vessel.